The HDP defines the body line of a Klinkhammer before attaching the wing base and the parachute hackle. The abdomen follows the curve of the hook shank, while the thorax occupies the front section. Make sure to leave enough room for the support and hackle wraps when selecting the size. For a caddis pupa, this same curve accommodates the abdomen beneath the thorax. Barbless and finished in Black Nickel, the HDP comes in packs of 25.